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Temporal and spatial evolution of damage zones along small-displacement faults adjacent to the seismogenic San Jacinto fault, southern California

Eliza Nemser

University of Washington, Department of Earth and Space Sciences

Seattle, Washington

[email protected]

Damage zones are characterized by deformation that accumulates in a volume around the fault core as a result of fault slip. Recent theoretical models of brittle fault-zone development based on principles of fracture mechanics describe the dependence of damage zone width on the velocity of crack propagation. According to these models, if fault development involves both quasistatic fault growth and dynamic slip, structures within the damage zone may record the distinctive signatures of these different fault behaviors. In this study, I use detailed field observations of the spatial and temporal relationships between structures within the damage zones of small-displacement faults with relatively little damage-zone complexity to investigate the history of fault slip. Small-displacement faults within the Pliocene-Pleistocene San Timoteo formation adjacent to the San Jacinto fault zone in southern California are ideal for this study as they are well-exposed and are reasonably inferred to have been seismically active.

AAPG Search and Discovery Article #90060©2006 AAPG Foundation Grants-in-Aid